I. Field of the Invention
The present invention relates to a method for the co-simulation of two or more mathematical models.
II. Description of Related Art
In the automotive industry, it is necessary to validate and calibrate the electronic control unit (ECU) for the vehicle which controls the overall operation of the major vehicle components. Traditionally, the approach for the calibration testing involves considerable real hardware and software systems that must work together in the final vehicle.
The basic purpose of calibration of an engine is to fine tune and optimize the operation of the engine for high performance, efficiency, fuel economy, low emissions, etc. This process is typically conducted in a laboratory environment before the installation of the engine in the vehicle for the final vehicle testing.
In a laboratory environment, the engine is mechanically coupled to a dynamometer which is a high performance electric motor that is mechanically coupled with the engine shaft. The dynamometer is able to run the engine in either of two operating modes, namely motoring and loading. In the motoring mode, the dynamometer is used to rotatably drive the engine so that the engine produces a theoretical negative torque for the dynamometer. After the vehicle has warmed up after running in the motoring mode for a period of time, the engine is switched on so that the engine rotatably drives the dynamometer shaft. In doing so, the dynamometer acts as an engine load.
In the loading mode, the load of the engine can be varied by controlling the speed of the dynamometer using the control system for the dynamometer. In doing so, technicians are able to simulate real world scenarios for the engine in terms of loading. These different scenarios include, for example, operating the engine under different road incline and speed conditions.
The calibration of the overall control for the engine consists generally of two separate parts. The first part includes the calibration software which runs on a separate computer, typically a PC, while the second part consists of the built in or dedicated hardware which interfaces the personal computer with the engine ECU. During this calibration phase, the software of the ECU can be modified as desired or required in order to achieve the desired engine operation.
One disadvantage of the previously known method for calibrating the ECU in an automotive vehicle is that the calibration system necessarily requires the use of real hardware when operating the engine with the dynamometer. Unless the real hardware is completed, ready, tested, and available, it has not been previously possible to carry out the calibration process. This, in turn, can undesirably extend the required time for the overall engine development.